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I 







/ 


HOUSE .... No. 1672 


Cfte CommontoealtJ) of S©as0aci)usett0. 



In Board of Gas and Electric Light Commissioners, 
Boston, Jan. 15, 1912. 

To the Honorable Senate and House of Representatives in General Court 

assernbled. 

* 

At the legislative session of 1910 the following order was adopted 
and transmitted to this Board: — 

Ordered, That the Board of Gas and Electric Light Commissioners 
shall investigate the operation of demand indicators, so called, used by 
electric light companies, and shall determine whether or not it is expedient 
to regulate or prohibit the use of such meters. Said Board shall report 
on this subject not later than January 15. 

Pursuant to this order the Board has made the investigation 
directed and, in connection therewith, on the sixth and twenty- 
seventh days of October, 1911, gave public hearings to all persons 
interested. Due notice of these hearings was given by publication 
in the Boston press and also to the persons who introduced the 
legislation which gave rise to this order, to the members of the 
Committee on Mercantile Affairs of the Legislature of 1911, who 
reported the order, to the mayor or selectmen of all municipalities 
in which electric light companies are engaged in business, to cer¬ 
tain business and civic associations who have been accustomed to 
interest themselves in such questions and to the electric light 
companies. 

In addition to the information developed at these hearings, the 
Board has directed inquiries to all the companies and municipalities 
engaged in the sale of electricity, relative to the extent arid pur- 







2 


INSPECTION OF DEMAND INDICATORS. [Jan. 


pose of the use of demand indicators and the means employed 
to ensure their accuracy. It has also employed Prof. F. A. Laws 
of the Massachusetts Institute of Technology to make an examina¬ 
tion into and report upon the mechanical and technical features of 
these appliances and to conduct a series of tests of Wright demand 
indicators, which are largely used by the Edison Electric Illumi¬ 
nating Company of Boston. 

His report in full, except the appendix thereto, which may be 
consulted at this office, constitutes Appendix A of this report. 

As a result of its investigation, the Board respectfully submits 
its report as follows: — 

Use of Demand Indicators. 

Upon inquiry of the companies and municipalities making re¬ 
turns to the Board, it appeared that 69 companies and 23 munici¬ 
palities had no demand indicators in use on June 30, 1911. Twelve 
companies and 4 municipalities had 11,613 demand indicators in 
use on that date, but of these 10,745 belonged to the Edison Elec¬ 
tric Illuminating Company of Boston, 303 to the Haverhill Electric 
Company, 291 to the Malden Electric Company, 86 to the Nor¬ 
wood Municipal Plant, 71 to the Salem Electric Lighting Com¬ 
pany, 53 to the Lowell Electric Light Corporation, 21 to the 
Fitchburg Gas and Electric Company, 17 to the Worcester Elec¬ 
tric Light Company and the remaining 26 to the other 5 companies 
and 3 municipalities. Of the demand indicators in use, 11,447 
were of the type known as “Wright Maximum Demand Indicators,” 
95 were of the type known as “Ingalls Relay Demand Indicators,” 
and 71 of the type known as “General Electric Maximum Watt 
Demand Indicators, Type W.” The Edison Company of Boston 
owned 10,745 of the Wright Demand Indicators and all of the 
Ingalls Relay Indicators. 

One or two companies have recently installed an appliance 
known as an “excess indicator,” which causes a noticeable in¬ 
terruption of service if more than a certain prearranged amount 
of electricity is required by a customer at any one time. One com¬ 
pany had 250 of these appliances in use on June 30, 1911. Such 
an “excess indicator,” however, is not a “demand indicator,” 
as this term is ordinarily used. It does not measure anything or 
determine any factor used in fixing the charge made for electricity 

iTas? T»? ^8 

t « 


ii 






HOUSE —No. 1672. 


3 


1912.] 




supplied to the customer, but serves to limit merely his use of the 
supply. For these reasons the Board has not included such “excess 

v 

indicators” in its investigation. 


Demand Indicators and their Operation. 

In the report made to the Board by Professor Laws, a copy of 
which is hereto annexed, entitled Appendix A, descriptions are 
given of the three types of demand indicators in use as above de¬ 
scribed. These descriptions are accompanied by sketches of the 
devices and explanations of their operation when in service, and 
are as concise as is consistent with clearness. It seems unnecessary 
to repeat them here, but to refer those desiring to know the tech¬ 
nical details of their mechanism and operation to his report. 

The Wright demand indicator, as will be seen by reference to 
his report, is in appearance a metal box with an index tube and 
scale exposed to view and its working parts enclosed. It is designed 
to register automatically by the rise of the liquid in the exposed 
index tube when a sufficient time to ensure its complete operation 
is allowed the volume of electric current delivered. In a two-wire 
service one such indicator is installed on the customer’s side of the 
recording watt hour meter, and in a three-wire service two in¬ 
dicators are so installed, one on each side of the neutral wire. 
Once installed it will register the greatest volume of current 
passing through it at any one time without, however, leaving any 
trace as to the time when this occurs. The registration is in am¬ 
peres, the technical unit of current strength or rate of delivery. In 
order to ascertain the power required by the customer at the time 
of the highest registration of the instrument, the amperage thus 
registered must in direct current use be multiplied by the voltage 
at which electricity is delivered to that service. The result in 
watts is often spoken of as the customer’s demand. In practice, 
immediately after the reading of this instrument is made and 
noted by the reader, it is reset by him. No trace of its indication 
remains and no opportunity exists for the subsequent verification 
of the same. This type of indicator costs less than other types, is 
inexpensive to operate and hence its more extensive use. 

It is intended that approximately 90 per cent, of the registra¬ 
tion of the volume of current introduced into the indicator shall be 
accomplished in four minutes, and the entire registration in about 


4 


INSPECTION OF DEMAND INDICATORS. [Jan. 


forty minutes. A fair approximation of the final registration, say 
85 per cent., occurs more promptly when the indicator is worked 
at about its full capacity than when it is lightly loaded. Each in¬ 
dicator has its characteristic rate of response to the current. Owing 
to differences in the tubes it is impracticable to use any printed 
standard scales for the different sizes of indicators. Each must be 
graduated by experiment to fit the particular tube to which it 
is applied. 

In the case of the Edison Company of Boston, demands on direct 
current services and on alternating current services where the 
load is non-inductive, as for illustration without alternating current 
motors, are determined by the Wright demand indicator, except 
in cases where electricity is sold under schedules D and D-l 1 of 
the rates of that company now in force. 

The Ingalls relay demand indicator is an auxiliary to the watt 
hour recording meter which registers the amount of electrical 
energy actually delivered to a customer. Such a recording watt 
hour meter is essentially a miniature motor driven by the current 
passing through it. In the Ingalls demand indicator the disc 
driven by this miniature motor in turn drives another wheel at a 
slower speed, and the revolutions of this wheel are recorded on a 
tape drawn at an even speed by clockwork. By this mechanism 
a continuous record is made by which the customer’s demand can 
be computed and determined for any hour of the period for which 
the indicator is set. This instrument is far more expensive to 
purchase and maintain than the Wright demand indicator, and is 
used by the Edison Company of Boston alone and only in con¬ 
nection with customers purchasing electricity under what is known 
as the “permanent electric rate” schedule. (See Appendix B, 
schedules D and D-l.) 

The General Electric Type W watt demand indicator is in out¬ 
ward appearance a watt hour meter, but, in place of the dials and 
hands by which the number of watt hours is recorded, there is but 
one dial with two hands and a scale registering in kilowatts from 
zero up, according to the capacity of the indicator. It is designed 
for use on alternating current circuits and for polyphase work 
only. In addition to the mechanism ordinarily found in a watt 
meter of the induction type, a second disc mounted on the same 
spindle rotates between two sets of magnets so arranged as to 


1 See Appendix B. 




1912.] 


HOUSE —No. 1672. 


5 


retard the speed at which the spindle may rotate in response to 
variations of the load. By a system of gearing the first hand is 
driven over the dial according to the amount of electrical power 
delivered, and pushes ahead of it a second hand, which is provided 
with a ratchet that holds it at the highest point to which it is 
pushed. At every diminution of the load the first hand falls back 
towards zero. This instrument records the greatest demand 
in kilowatts made by the customer at one time, but gives no indi¬ 
cation of the time when it occurs; it is intended that the magnets 
be so set that 90 per cent, of the registration is attained in five 
consecutive minutes. The original cost and expense of main¬ 
tenance of this type is much greater than that of the Wright de¬ 
mand indicator already described. 

Mechanical Accuracy in Actual Use. 

Of the 16 companies and municipalities using demand indicators, 
10 reported that they tested the appliances before installation and 
6, that they did not. Eight reported that no tests of the appliances 
were made after they were installed, 3 made occasional tests, 3 
tested the appliances whenever a customer demanded such test 
and 2 made periodic tests. Of the 2 making periodic tests, one 
had but two demand indicators in use and these were tested once a 
year. The other, the Edison Company of Boston, examines and 
tests the indicators before installation. After installation this 
company has a system of routine inspection by which one-quarter 
of the number in use are returned to the company’s laboratory 
every year for verification and such correction and repairs as may 
be found necessary. During the year ending June 30, 1911, this 
company reports that 2,830 indicators were removed from the 
customers’ premises in this regular routine and were tested. In 
addition all new indicators purchased and all indicators removed 
from customers’ premises for reasons other than in the regular 
routine were tested when brought in and the total number of all 
tests of such indicators during that year was 4,184. 

As already stated, Professor Laws made a series of tests of the 
Wright maximum demand indicators in use by the Edison Com¬ 
pany of Boston in order to ascertain their accuracy under ordi¬ 
nary service conditions. Eighty-one indicators of sizes varying 
from 5 to 300 amperes were selected by him at random, removed 


6 


INSPECTION OF DEMAND INDICATORS. [Jan. 


from the premises where installed in his presence or in the presence 
of his assistant taken to the Standardizing Laboratory of the 
Massachusetts Institute of Technology and there tested. 

His report of these tests is as follows: — 

At the laboratory the indicators of a given size were set up and connected 
in series; currents, either direct or alternating, as the case required, and 
of the proper magnitude, were sent through them and maintained constant 
until the readings assumed their ultimate values. The currents were 
measured by the use of standards certified by the United States National 
Bureau of Standards at Washington, D. C. 

The points selected for calibration were: first, 20 per cent, and 90 per 
cent, of the full scale reading, the former because it is usually the first 
mark on the scale, the latter because it is desirable to be able to state the 
inaccuracy at the upper end of the scale if the indicator should register 
too much; second, two intermediate points at about 43 per cent, and 66 
per cent, were taken, thus dividing the interval between 20 per cent, and 
90 per cent, about equally. Tests were made at these four points and 
then, in order to obtain a check measurement, the whole series was 
repeated. All tests were made at a room temperature of 68 degrees F., 
unless otherwise specified. 

As the 20 per cent, loadmark is the first one on the scale, no numerical 
reading is possible unless the indicator is correct or reads too much; so 
in the first table following it is simply noted whether the reading is too 
large, correct or too small. The average registration of those indicators 
which register too much at this point is 113.5 per cent. If those regis¬ 
tering correctly be included, the average is 108.7 per cent. The readings 
at the lower end of the scale are considerably influenced by temperature: 
for instance, four indicators of 35 amperes capacity were set ac 68 degrees 
F., and then the temperature raised to 104 degrees F., and kept there for 
four hours, no current being sent through the indicators; the average rise 
of the liquid in the indicator tubes was .52 inch, which roughly corresponds 
to a change of reading of 5 amperes at this point. These extremely low 
readings are not, however, of as great importance as those at the upper 
end of the scale. For example, it happens that the average percentage 
reading of the indicators when removed for test was approximately 60 
per cent., with an occasional value falling as low as 30 per cent. The 
effect of temperature becomes smaller as the readings increase. 


1912.] 


HOUSE —No. 1672. 


7 


The following tables show the results of the tests: — 


At 20 Per Cent. Load. 


Rating of Indicators (Amperes). 

Number of 

WHICH REGI 

Much. 

Indicators 
ster TOO — 

Little. 

Number 
which register 
correctly. 

5.. . . 

6 

2 

0 

10. 

3 

3 

4 

15. 

5 

3 

2 

25. 

5 

4 

1 

35. 

1 

3 

0 

50,. 

7 

2 

1 

75. 

3 

4 

3 

100,. 

3 

1 

1 

150,. 

3 

0 

4 

200. 

0 

2i 

4i 

300. 

0 

1 

0 

Totals,. 

36 

25 

20 


1 At 25 per cent, load being first mark on scale of this indicator. 


44.5 per cent, of the indicators register too much. The average excess registration is 13.5 per 
cent. 

30.9 per cent, of the indicators register too little. 

24.7 per cent, of the indicators register correctly. 

Average excess registration of indicators which register correctly and too much, 8.7 per cent. 

























8 


INSPECTION OF DEMAND INDICATORS. [Jan 


At 43 Per Cent. Load. 


Number of Indicators registering — 


Rating 
of Indicators 
(Amperes). 

110 Per 
Cent, and 
More. 

109.9-105.1 
Per Cent, 
inclusive. 

105-102 
Per Cent, 
inclusive. 

101.9-98.1 
Per Cent, 
inclusive. 

98-95 
Per Cent, 
inclusive. 

94.9-90.1 
Per Cent, 
inclusive. 

90 Per 
Cent, and 
Less. 

5, . . . 

0 

0 

2 

4 

2 

0 

0 

10, . . . 

0 

2 

2 

4 

0 

1 

1 

15, . . . 

0 

0 

3 

3 

4 

0 

0 

25, . . . 

0 

0 

2 

6 

1 

1 

0 

35, . 

1 

0 

2 

0 

0 

1 

0 

50, . 

3 

3 

2 

1 

0 

1 

0 

75, . . . 

1 

0 

1 

4 

4 

0 

0 

t—‘ 

O 

O 

0 

1 

2 

2 

0 

0 

0 

150, . 

1 

3 

0 

2 

0 

1 

0 

200, . 

0 

0 

0 

5 

0 

1 

0 

300, . 

0 

0 

0 

0 

0 

0 

1 

Totals, 

6 

9 

16 

31 

11 

6 

2 


71.6 per cent 
18.5 per cent 
9.9 per cent 


of the indicators register between 95 per cent, and 105 per cent, 
of the indicators register more than 105 per cent, 
of the indicators register less than 95 per cent. 


At 66 Per Cent. Load. 


Number of Indicators registering — 


Rating 
of Indicators 
(Amperes). 

110 Per 
Cent, and 
More. 

109.9-105.1 
Per Cent, 
inclusive. 

105-102 
Per Cent, 
inclusive. 

101.9-98.1 
Per Cent, 
inclusive. 

98-95 

Per Cent, 
inclusive. 

94.9-90.1 
Per Cent, 
inclusive. 

90 Per 
Cent, and 
Less. 

5, . . . 

0 

0 

1 

2 

4 

1 

0 

10, . 

0 

1 

3 

4 

1 

1 

0 

15, . . . 

0 

0 

2 

2 

6 

0 

0 

25, . . . 

0 

0 

1 

7 

1 

1 

0 

35, . 

1 

0 

1 

1 

1 

0 

0 

50, . 

2 

1 

4 

3 

0 

0 

0 

75, . 

1 

0 

4 

3 

2 

0 

0 

O 

O 

T-H 

0 

1 

2 

2 

0 

0 

0 

150, . 

1 

1 

2 

2 

1 

0 

0 

200, . 

0 

0 

2 

4 

0 

0 

0 

O 

O 

CO 

0 

0 

0 

0 

0 

1 

0 

Totals, 

5 

4 

22 

30 

16 

4 

0 


84.0 per cent, of the indicators register between 95 per cent, and 105 per cent. 
11.1 per cent, of the indicators register more than 105 per cent. 

5.0 per cent, of the indicators register less than 95 per cent. 
























































1912.] 


HOUSE —No. 1672. 


9 


At 90 Per Cent. Load. 


Number of Indicators registering 


Rating 
of Indicators 
(Amperes). 

110 Per 
Cent, and 
More. 

109.9-105.1 
Per Cent, 
inclusive. 

105-102 
Per Cent, 
inclusive. 

101.9-98.1 
Per Cent, 
inclusive. 

98-95 

Per Cent, 
inclusive. 

94.9-90.1 
Per Cent, 
inclusive. 

90 Per 
Cent, and 
Less. 

5, . . 

0 

0 

1 

5 

1 

1 

0 

10. . . . 

1 

0 

1 

5 

2 

1 

0 

15, . . . 

0 

0 

1 

7 

2 

0 

0 

25, . . . 

0 

0 

1 

6 

2 

1 

0 

35, . 

0 

2 

0 

2 

0 

0 

0 

50, . 

0 

3 

4 

2 

1 

0 

0 

75, . . . 

1 

0 

1 

6 

2 

0 

0 

100, . 

1 

1 

0 

3 

0 

0 

0 

150, . 

2 

0 

3 

0 

2 

0 

0 

200, . 

0 

0 

3 

3 

0 

0 

0 

300, . 

0 

0 

0 

0 

0 

1 

0 

Totals, 

5 

6 

15 

39 

12 

4 

0 


81.5 per cent 

13.6 per cent 
5.0 per cent 


of the indicators register between 95 per cent, and 105 per cent, 
of the indicators register more than 105 per cent, 
of the indicators register less than 95 per oent. 


Disregarding the readings obtained at 20 per cent, load for the 
reasons suggested by Professor Laws, and applying the same rule 
as provided by law for electric meters, namely, that the instrument 
be deemed correct if it does not vary more than 5 per cent, from 
the standard, it appears that of the 81 indicators tested at 43 
per cent, load, 58 were correct, 15 registered too much and 8 too 
little, and at 90 per cent, load, 66 were correct, 11 registered too 
much and 4 too little. 

Purpose for which used. 

In every instance where demand indicators are employed they 
are used to determine the greatest demand a customer makes 
during a given period upon the capacity of the generating plant 
and distributing system by which he is served. In several cases 
this demand is ascertained solely for the private information of 
the management of the company as an aid to determine the size 
of transformers, meters or conductors. In others it is used as a 
check upon a demand determined or estimated in some other 
way. In the majority of instances the maximum demand of the 


























10 INSPECTION OF DEMAND INDICATORS. [Jan. 


customer ascertained by these indicators is one factor, and often 
an extremely important factor, to the customer in the charge 
made him for his supply of electricity. 

Two methods of utilizing the customer’s maximum demand 
are employed in making their charges by companies and munic¬ 
ipalities using demand indicators. Some make a definite fixed 
charge per kilowatt of maximum demand and an additional charge 
per kilowatt hour for electricity consumed. Others charge the 
equivalent of a certain number of hours’ use of the demand per 
month at one price and all in excess thereof at a lower price or 
prices. 

The Edison Company of Boston employs both of these methods. 
In its so-called “yearly lighting rates,” and “permanent electric 
rates,” a fixed yearly price payable in equal monthly instalments 
is charged for each kilowatt of maximum demand, and in addition 
a price is charged for each kilowatt hour of electricity consumed. 
In its “power rates” all electricity furnished up to twenty-three 
hours’ use per month of the customer’s maximum demand is 
charged at 12 cents per kilowatt hour, and lower prices and dis¬ 
counts are made for all electricity consumed per month in excess 
thereof. The demand in the “yearly lighting rates” for each year, 
beginning the first of February, is the highest reading of the de¬ 
mand indicators during the preceding three months, and in the 
“power rates,” the average of such readings during the preceding 
four months. The demand in the “permanent electric rates” is 
fixed in the first instance by agreement with the customer, but 
must be at least 50 kilowatts; a continuous record of the demand 
is recorded by the Ingalls indicator, already described, and the 
charge made accordingly. 

Existing Provisions of Law. 

In 1901 the Legislature enacted chapter 497, entitled “An Act 
to provide for the Inspection of Electric Meters.” The provisions 
of this chapter are now sections 36 (amended by chapter 348 of 
the Acts of 1911), 37 and 38 of chapter 121 of the Revised Laws. 
These sections read as follows: — 

Section 36. A customer of an electric lighting company or such 
company may apply to the board of gas and electric light commissioners 
for an examination and test of any meter in use upon a customer’s prem- 


1912.] 


HOUSE —No. 1672. 


11 


ises. The board shall forthwith cause to be made by a competent and 
disinterested person such examination and test of said meter as in the 
judgment of the board is practicable and reasonable, and shall furnish 
to the company and to the customer a certificate of the result and expense 
thereof. If upon such examination it appears that the meter does not 
register correctly, the board may order the company to correct or remove 
such meter and to substitute a correct meter therefor. All fees for exam¬ 
inations and tests shall in the first instance be paid by the person or 
company making application therefor; but if the examination or test is 
made at the request of a customer and the meter is found to be incorrect 
because too fast, the company shall pay such fees to the board, to be repaid 
by it to the applicant. A meter shall be deemed correct for the purposes 
of this section if it appears from such examination or test that it does 
not vary more than five per cent, from the standard approved by the 
board. 

Section 37. The person designated to make such inspection may at 
any reasonable time enter upon any premises where the meter to be 
inspected is placed, for the purpose of making the inspection. He shall 
receive such compensation for his services as the board may determine, 
together with his necessary travelling and other expenses, which shall be 
audited by the board and paid from the treasury of the commonwealth; 
but the total amount of compensation and expenses shall nob exceed three 
thousand dollars in any year; and if the total amount of such compen¬ 
sation and expenses shall in any year exceed the amount of the fees 
received for such examinations and tests, the excess shall be assessed and 
recovered from the electric light companies in the manner now provided 
for the assessment and recovery of the other expenses of the board. All 
money received for fees for such examinations and tests shall be paid 
into the treasury of the commonwealth by the board quarterly on the 
first Mondays of January, April, July and October of each year. 1 The 
board may establish such rules and regulations, fix such standards, pre¬ 
scribe such fees and employ such means and methods in, and in connec¬ 
tion with, such examinations and tests of electric meters as in the judg¬ 
ment of the board shall be most practicable, expedient and economical. 
The board may purchase such materials, apparatus and standard measur¬ 
ing instruments for such examinations and tests as it may deem necessary. 

Section 38. In the two preceding sections the word “company” or 
“companies” shall include every person, partnership, association, cor¬ 
poration and municipality engaged in the sale of incandescent electric 
light or electricity for incandescent lighting. 

In administering this law the Board has always construed it as 
applying to meters measuring the electrical energy delivered to 
the customer. No application was made to the Board prior to 


i By chapter 318 of the Acts of 1909, on the last business day of each month. 



12 INSPECTION OF DEMAND INDICATORS. [Jan. 


1910 for the examination and test of demand indicators under the 
claim that they are “meters” within the meaning of the provisions 
of these sections. The Board had then and still has serious doubts 
whether the Legislature intended to include “demand indicators” 
or any similar device by the use of the word “meters.” 

In 1909 chapter 412 entitled, “An Act relative to the Adjustment, 
Testing and Sealing of Weighing and Measuring Devices used for 
Hire or Reward,” it is provided as follows: — 

Section 1 . The provisions of chapter sixty-two of the Revised Laws, 
relating to the adjustment, testing and sealing of weights, measures and 
balances shall apply to all weighing and measuring devices used for the 
purposes of weighing and measuring for hire or reward. 

Section 2. A sealer or deputy sealer shall seal such devices when 
they are tested and found correct, and shall mark, condemn, or seize such 
devices if found incorrect, in accordance with the provisions of said chapter 
sixty-two applicable to weights, measures and balances; and all penalties 
imposed by said chapter for violation of the provisions thereof relative to 
weights, measures and balances shall also apply to the devices aforesaid. 

At the hearings it was suggested that “demand indicators” were 
“measuring devices” within the meaning of this chapter. The 
Board was also informed that this claim had been made to the 
Commissioner of Weights and Measures and that he had been re¬ 
quested to test and seal a demand indicator installed by the 
Edison Company of Boston upon the premises of one of its cus¬ 
tomers. The Commissioner of Weights and Measures requested 
an opinion of the Attorney-General as to his duties and authority 
with respect to the matter, but no ruling has been made prior 
to the date of this report. 

Conclusions and Recommendations. 

At the hearings held by the Board, aside from the representa¬ 
tions and arguments presented in behalf of the companies in favor 
of the continuance and desirability of the use of demand indicators, 
there was a considerable variance in the view expressed. One of 
the chief advocates of the legislation proposed at the last session 
of the General Court, which gave rise to this investigation, favored 
legislation for the periodic examination, sealing and testing of 
demand indicators in similar manner to the adjustment, testing 
and sealing of weights, measures and balances. His complaint was 
chiefly as to the accuracy of the Wright demand indicators in use 


1912.] 


HOUSE —No. 1672. 


13 


by the Edison Company of Boston and not to the use made of 
the demand, if correctly determined, in the company’s system of 
rates. Another customer of the same company complained as 
earnestly, not of the possible inaccuracy of the indicators, but of 
the system of charging based on the demand of the customer de¬ 
termined by the use of indicators or, for that matter, in any other 
way. Other large users of electricity supplied by the same com¬ 
pany under its system of differentials sent their representative to 
advocate the continuance of the use of demand indicators and of 
the demand system of charging, claiming that a differential scale 
of prices in the sale of electricity is reasonable and necessary. Still 
others, representing residential sections of the city, upon finding 
that demand indicators were used by the Edison Company only 
with respect to customers paying a price per kilowatt hour less 
than the standard or maximum net price offered to all customers 
for any use, restricted their opposition to demand indicators to 
their use in residences. 

In the explanation which has been made with respect to the 
character of these appliances and the purpose for which they are 
used in the supply of electricity, it is hoped that the Board has 
made clear that, so far as concerns the customer, they help to as¬ 
certain one factor in what is known as a demand system of charge. 
Where such a system prevails a certain price is made for the cus¬ 
tomer’s demand, however determined, as distinguished from, and 
usually in addition to, the price made for the electricity consumed 
measured by a watt-hour recording meter. It is perhaps obvious 
that where such a system of charge prevails, as the ratio of a cus¬ 
tomer’s consumption to his demand for any given period increases, 
the average cost per unit of the electricity consumed decreases, 
and that consequently two customers having the same demands 
but unequal consumptions of electricity for a given period will pay 
different average prices for their respective supplies, even though 
each pays the same price per kilowatt of demand and the same 
price per kilowatt hour consumed. This is of course describing 
the system in its essential and simplest form and not with respect 
to any of the varied applications of the system which appear in 
the rate schedules of the companies and municipalities using it, 
especially those of the Edison Company of Boston. 

In other words, the use of demand indicators is directly and 
intimately associated with differential rates for electricity. In 


14 INSPECTION OF DEMAND INDICATORS. [Jan. 


fact there is no occasion for their use except to secure, through the 
relation of consumption to demand, prices lower than the standard 
or ordinary prices charged by the company. To put the matter 
more concretely, the Edison Company of Boston reported that its 
customers numbered 38,321 on June 30, 1911, and yet it has but 
10,745 demand indicators in use. Although the demand in the 
case of alternating current power customers is for the most part 
determined otherwise than by demand indicators, it is a fair in¬ 
ference from these figures that nearly 70 per cent, of the com¬ 
pany’s customers cannot take advantage of the differential rates, 
but must pay the maximum net price and there is, therefore, no 
occasion for using demand indicators in supplying them. It fol¬ 
lows that of all customers only the comparatively small minority 
who get the benefit of differential rates, and who to a considerable 
extent are not dependent upon the companies for their supply, 
are the ones who are directly interested in the use of demand in¬ 
dicators. The large majority of customers are dependent on the 
companies for their supply, but are not directly interested in the 
demand indicator except as by its use or by the prohibition or re¬ 
striction thereof a lower maximum price for electricity may be 
secured to them. 

In 1908, after an investigation of the Edison Company’s rates, 
in the course of which the demand system, then far more exten¬ 
sively applied by the company, was explained and discussed, the 
Board, while unable to accept the company’s theory in justifica¬ 
tion for differential rates, recognized the commercial necessity 
in the present development of the industry of making prices for 
large or long-hour users of electricity, whether for light or power, 
sufficiently low to attract the business. The problem of the com¬ 
pany was to increase its output without a proportionate increase 
in investment. This could be accomplished, however, only through 
far more extended and varied applications of electricity which 
would bring the company into very direct competition with the 
cost to prospective customers for light, heat or power otherwise 
obtainable. In fact, as the Board then stated, the only means by 
which the average lighting customer may hope to have the price 
to him materially reduced is through such development of the com¬ 
pany’s business. The price at which electricity can be offered was 
and still is an essential feature in the solution of this problem. The 
Board at that time made no recommendations as to the differential 


1912.] 


HOUSE —No. 1672. 


15 


features of the company’s schedules, but recognized “as existing 
certain economic conditions attending the sale of electricity which, 
in the interest of the many whose needs and convenience the com¬ 
pany should serve, seem to warrant a continuance of certain dif¬ 
ferences in prices, not as a permanent policy, but until the uniform 
rate recommended can, from time to time, be safely reduced so 
low as to be in itself an encouragement to the unrestricted use of 
electricity for all purposes.” 

The Board has found no sufficient reason for changing the views 
then expressed. It has, both with respect to the Edison Com¬ 
pany and all others under its supervision, consistently pursued the 
policy, by the exercise both of its authority and its influence, to 
force reductions in the maximum prices at which any person in the 
territory occupied by any company may be supplied with elec¬ 
tricity for any use. At the same time it has as consistently de¬ 
clined either to direct changes in, to endorse or to condemn dif¬ 
ferential prices offered by the companies, insisting however that 
all prices shall be open to all who may apply for service and that 
special and secret rates and direct or indirect rebates or preferences 
shall be discontinued. 

The demand system of rates is, of course, not the only system 
employed for making differential prices. The present way in 
which the demand system of the Edison Company of Boston is 
applied is by no means the only way in which such a system may 
be used. For that matter, demand indicators may not be essential 
to a demand system of rates, although no satisfactory mechanical 
substitute for them in that relation is known to the Board. After 
carefully noting the various schedules of rates of the companies 
under its supervision and their effect upon revenues, output and 
operating efficiency, two things are evident, namely, that the 
men engaged in the business seem agreed upon the present neces¬ 
sity for differential rates, and yet that there is no general agree¬ 
ment among them as to the theory or practice upon which such 
differential rates should be based. The Board believes that the 
available experience is not yet sufficient for reaching any just or 
final conclusion as to the expediency of prohibiting or restricting 
differential rates. The use of demand indicators, as already pointed 
out, is so intimately involved in this problem that, for like reasons, 
it seems at present inexpedient to prohibit or restrict their use. 
On the other hand, the Board is emphatically of the opinion that 


16 INSPECTION OF DEMAND INDICATORS. [Jan. 


it is not in the public interest that any legislative sanction or 
approval, directly or indirectly, shall be given to differential rates. 

With respect to the “regulation” of demand indicators, the 
Board has assumed that this expression in the order refers to some 
means of ensuring their accuracy. The description given of the 
various types of indicators in use has perhaps made evident some 
of the difficulties attendant upon applying to them the same rules 
for adjustment, testing and sealing as apply to weights, measures 
and balances or even to gas meters. The calibration of the Wright 
demand indicators prior to installation, for reasons already set 
forth in the description of this type, fairly constitutes a part of 
the initial cost of these instruments. The correct adjustment of 
the other types prior to installation is a necessary incident to their 
use. But in each instance, owing to the character of the mechan¬ 
ism and the necessary manipulation of the device from time to 
time by the companies’ employees, there is no practicable method 
of sealing them prior to installation with any assurance that their 
operation in use may not be altered or affected by changes in sur¬ 
rounding conditions without detection. No satisfactory test of 
the Wright demand indicators especially can be made upon the 
premises where installed, due to the impracticability of keeping 
the conditions necessary for such test constant. 

Any provision of law requiring the examination, testing and 
sealing of demand indicators by a public official must necessarily 
rest upon a purpose to protect purchasers of electricity from over¬ 
charging by the use of indicators allowed to operate incorrectly. 
To be effective to this end, the method of inspection employed 
either must reasonably assure the customer that the operation of 
the indicators after installation by the seller cannot be readily 
altered or otherwise affected without detection while the same 
are in use upon his premises, and before another examination and 
test is made by the public official charged with this duty, or must 
provide a heavy penalty whenever the seller is found to be em¬ 
ploying and maintaining an indicator operating incorrectly and 
adversely to the customer. The examination of demand indicators 
made by the Board has convinced it that, if properly constructed, 
and calibrated, and properly handled and inspected by the com¬ 
panies’ employees while in use upon customers’ premises, they 
may be expected to operate correctly within certain reasonable 
limits. On the other hand, the Board is equally convinced that 


1912.] 


HOUSE —No. 1672. 


17 


it is not practicable to test and seal these appliances in the 
manner long pursued with respect to gas meters, or to apply 
the methods employed in the periodic adjustment, exami¬ 
nation, testing and sealing of balances, weights and measures. 
Any attempt to do so would also involve an expense and the or¬ 
ganization and maintenance of an inspection force hardly com¬ 
mensurate with the possible good accomplished, especially in 
view of the limited number of demand indicators in actual use and 
of the fact that reductions in the maximum net price charged for 
electricity tend to further reduce this number. It has also been the 
experience of the Board that the chief complaint is not with the 
mechanical accuracy of the device itself, but rather with the 
system of charging in which it is used. No amount of examination 
and testing will satisfy every customer who complains of a demand 
recorded for a brief period, of which he has no personal knowledge, 
but which is made the basis of the charge to be made him for the 
succeeding year of his supply. This is an inherent difficulty with 
any system of rates based upon a maximum demand mechanically 
determined, but the same or greater difficulties arise in ascertain¬ 
ing the demand in any other way known to the Board. 

The Board recommends that the provisions of sections 36, 37 
and 38 of chapter 121 of the Revised Laws be extended to demand 
indicators and all other mechanical devices and appliances used 
in determining the charge to be made by companies and municipali¬ 
ties supplying electricity, save that the examination and test of 
the same need not be made upon the customer’s premises; that a 
penalty be imposed whenever, upon examination and test, a meter, 
demand indicator or other device or appliance so used is found to 
operate or register incorrectly and adversely to the customer; 
and that it be expressly stipulated that by such action no sanction 
or justification is intended to be given differential or discriminatory 
prices for electricity. A bill embodying the Board’s recommenda¬ 
tion accompanies this report. 

Respectfully submitted, 

FORREST E. BARKER, 
MORRIS SCHAFF, 

ALONZO R. WEED, 

Board of Gas and Electric Light Commissioners. 


18 INSPECTION OF DEMAND INDICATORS. [Jan. 1912. 


An Act to provide for the Inspection of Demand Indicators. 

Section 1 . The provisions of sections thirty-six, thirty-seven and 
thirty-eight of chapter one hundred and twenty-one of the Revised Laws 
and of all acts in amendment thereof and in addition thereto shall apply to 
demand indicators, so called, and any other devices or appliances installed 
by an electric company upon the premises of any of its customers and used 
by such company for the purpose of determining the charge to such cus¬ 
tomer for its service. Nothing herein contained shall be held to authorize 
or justify differential prices for electricity supplied by such company. 

Section 2. Whoever being engaged in the sale of electricity maintains 
upon the premises of a customer a meter, demand indicator or other 
mechanical device or appliance for the purpose of determining the charge 
to be made for electricity supplied to such customer, which meter, demand 
indicator or other mechanical device or appliance is found upon examina¬ 
tion and test, as provided in section thirty-six of chapter one hundred and 
twenty-one of the Revised Laws, to register incorrectly as against such 
customer, shall for each offence be punished by a fine of not more than 
twenty-five dollars. 

Section 3. All provisions of law inconsistent herewith are hereby 
repealed. 

Section 4. This act shall take effect upon its passage. 


APPENDICES. 












Fig. 1.—Wright Maximum Demand Indicator 


















Appendix A. 


REPORT TO BOARD OF GAS AND ELECTRIC LIGHT COM¬ 
MISSIONERS ON MAXIMUM DEMAND INDICATORS IN 
USE BY THE EDISON ELECTRIC ILLUMINATING COM¬ 
PANY OF BOSTON, DECEMBER, 1911, BY F. A. LAWS. 

; In cases where it is necessary to determine a customer’s maximum 
demand, the practice of the Edison Electric Illuminating Company 
of Boston is as follows: — 

All demands on direct current services and all demands on alter¬ 
nating current services, if the load be noninductive (that is, where 
alternating current motors, rectifiers, etc., are not used), are deter¬ 
mined by means of the Wright Maximum Demand Indicator except in 
cases where electricity is sold under schedule D of the schedule of 
rates published by that company June 1, 1910 (Appendix B). 

In all cases where schedule D is in force, for either direct or alter¬ 
nating current services, and for all alternating current power above 
50 kilowatts, the Ingalls Relay Demand Indicator is used. 

In general, for alternating current power under 50 kilowatts no 
permanent device is installed; the demand is commonly determined 
by timing, at intervals, the regularly installed watt-hour meter with 
a stop watch while the machinery is running at its normal maximum, 
or else an Ingalls Relay Demand Indicator, is temporarily installed 
and the demand so determined. Occasionally, however, this indicator 
is made a permanent fixture. There are, therefore, two devices in 
use by this company for determining maximum demands: — 

1. The Wright Maximum Demand Indicator. 

2. The Ingalls Relay Demand Indicator. 

The Wright Maximum Demand Indicator. 

This indicator may be looked upon as a registering differential ther¬ 
mometer, one bulb of which is heated by the passage of the current 
through a suitable heater coil which closely surrounds it. 

The internal appearance of the indicator as made in the smaller 
sizes, up to and including 25 amperes, is shown in Fig. 1. 



99 


APPENDIX A. 


[Jan. 


The essential working parts are the indicator tube, with its attached 
index tube (i 2 ), the scale (s) and the heater strips (c). In the small 
sizes (up to and including 25 amperes) the customer’s entire current 
is taken in through the leads (L,L), and to the heater strips via the 
spring hinges (h) and flexible connecting strips (k). 

The Indicator Tube. — The indicator tube (see Fig. 2) is of glass, 
annealed so that it will bear handling and not be subject to changes 
due to stresses in the glass; the two bulbs (bi and b 2 ) which are nearly 
equal in volume, contain air, the U tube connecting them contains 
concentrated sulphuric acid in such an amount and so adjusted in the 
tube that when the indicator is cold and set ready to begin to operate, 
the level of the liquid is at d, so that it is just on the point of flowing 
into the index tube (i 2 ). Sulphuric acid is used because it “wets” 
the glass, is very heavy, flows readily, is hygroscopic and expands 
comparatively little with rise of temperature. To prevent accidental 
transfer of air from bi to b 2 or vice versa, especially when the indi¬ 
cator is set, the tube is constrictej to a capillary at g and g' and two 
traps are provided at t and t'. 

Heater Strips. — The heater strips are of an alloy of high resistivity, 
the resistance of which is but little affected by temperature; the 
strips are of very thin metal and are made to closely embrace the 
cylindrical glass bulb (bi) by means of screw clamps. (See Fig. 3.) 
In the small-sized indicators, where it is necessary to carry the heater 
strips around the bulb a number of times, a non-inductive form, shown 
at A in Fig. 3, is used. The object of this construction is to prevent 
the turns drawing together when a short circuit occurs; if this should 
happen the strips would very likely be burned out or their intimacy 
of contact with the glass so altered that an error would be introduced. 
The corrugated copper terminals form somewhat flexible electrical 
connections to the heater proper. In indicators having a range of 
35 amperes and above, shunts are used, the heater strips being of the 
15-ampere type. 

Setting and Operation. — The indicator is set by raising the lower 
end of the tube board (m), on which the above described members 
are mounted, until it is somewhat above the spring hinges (h) on 
which it is pivoted. This allows the liquid in the index tube (i 2 ) to 
drain back into the U tube; when thoroughly drained and the board 
is lowered to its normal position, the U tube is filled with liquid up 
to d. 

If a current is now sent through the heater strips, the air in bi is 
heated, and expands, causing the liquid to flow slowly into the index 
tube (i 2 ) which is in front of the graduated scale; the flow will continue 


























































































































































































































































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1912.] 


HOUSE —No. 1672. 


23 


until the permanent state of temperature corresponding to that par¬ 
ticular current is reached. 

Time-lag. Owing to the heat capacity of the strips, the glass 
bulb, etc., and the poor thermal conductivity of the glass, the response 
of the indicator to the increase of current is sluggish; this lagging of 
the reading behind the increase of current is essential to the success¬ 
ful operation of any such device, for it must not take cognizance of 
currents above the normal, which last for only a very short time. 
The indication desired is that due to the sustained maximum. Fig. 4 
shows this gradual increase of reading when the current is kept con¬ 
stant. Another point may be noted: after the device has cooled 
down, owing to shutting off the current, there will be no increase of 
reading when a current slightly larger than that previously registered 
is turned on until the larger current has been maintained for a time 
longer than the normal time-lag of the indicator; for that time must 
elapse before there has been sufficient expansion of the air in b t to 
cause the liquid to again begin to flow into the index tube. (This is 
illustrated in Fig. 5.) Curve A shows the normal rise of the indica¬ 
tion, when, after the device has been set, the current is maintained at 
10 amperes. After the current has been thrown off and the indicator 
allowed to cool thoroughly, a run at 10.5 amperes gives curve B (the 
indicator not being reset). 

It is intended that approximately 90 per cent, of the full load regis¬ 
tration be accomplished in four minutes, and the entire registration 
in about forty minutes. Fig. 4 shows how a particular instrument 
responded to the current. 

It will be noted from Fig. 4 that the rise to a fair approximation to 
the final reading, say 85 per cent, of it, occurs more abruptly when 
the indicator is worked at about its full capacity than when it is lightly 
loaded. Fig. 6 illustrates this point; a 50 and a 100 ampere indicator 
were tested in series at 45 amperes. Of course each indicator has its 
characteristic rate of response to the current. 

Owing to differences in the tubes, it is impracticable to print the 
scales, for each must be graduated by experiment to fit the particular 
tube to which it is applied. It is the practice of the Edison Company 
to determine either 4 or 5 points by passing measured currents through 
the indicator for a sufficient time, and then marking on the scale the 
corresponding heights of the liquid in the index tube (i 2 ); the sub¬ 
division is done mechanically. Samples of the scales used by this 
company are shown in Fig. 7; the points which are experimentally 
determined are marked by a heavy dot. 

The indicators are connected in circuit as shown in Fig. 8. 


24 


APPENDIX A. 


[Jan. 


It is the present practice of the Edison Company to bring in yearly 
for test and whatever adjustment is necessary, one-fourth of the Wright 
Demand Indicators which it has installed on its lines. The work is 
usually done in the eight months, March-October, inclusive. 

Tests. — The standard specifications for the purchase of Wright 
Demand Indicators include this statement as to the accuracy which 


the device should possess: — 

Per Cent. 

At full scale,.4 

At four-fifths scale,.5 

At three-fifths scale,.6§ 

At two-fifths scale,.10 

At one-fifth scale,.20 


The understanding is that the average accuracy of any 10 instru¬ 
ments shall be 3 per cent, or better at full scale reading at the time of 
purchase. 

The Edison Company has installed on its lines about 10,600 Wright 
Demand Indicators, of which approximately 99 per cent, are included 
in the sizes from 5 amperes to 200 amperes, inclusive, and the 300- 
ampere size. From these sizes the indicators to be tested were selected. 
The remaining 1 per cent, includes indicators of various capacities up 
to 3,000 amperes. 

The indicators to be tested were selected as follows: I was given 
access to the cases in which the meter readers’ cards are filed. From 
these I drew cards at random until the desired number of indicators 
of any specified size was reached. In the drawing, care was taken to 
retain only indicators which were actually used by the company in 
computing the bills of customers. Light and power and alternating 
as well as direct current services were represented in the selection. 

The numbers drawn as above were recorded, and the indicators 
removed from the customers’ premises, either in my presence or in 
the presence of my representative. They were immediately trans¬ 
ferred to the Standardizing Laboratory of the Massachusetts Institute 
of Technology, where the tests were made. 

At the laboratory the indicators of a given size were set up and con¬ 
nected in series, currents, either direct or alternating as the case 
required, and of the proper magnitude were sent through them and 
maintained constant until the readings assumed their ultimate values. 
The currents were measured by the use of standards certified by the 
United States National Bureau of Standards at Washington, D. C. 

The points selected for calibration were: first, 20 per cent, and 90 
per cent, of the full scale reading, the former because it is usually the 





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1912.] 


HOUSE — No. 1672. 


25 


first mark on the scale, the latter because it is desirable to be able to 
state the inaccuracy at the upper end of the scale if the indicator 
should register too much; second, two intermediate points at about 
43 per cent, and 66 per cent, were taken, thus dividing the inter¬ 
val between 20 per cent, and 90 per cent, about equally. Tests were 
made at these four points and then, in order to obtain a check measure¬ 
ment, the whole series was repeated. All tests were made at a room 
temperature of 68 degrees F., unless otherwise specified. 

The results obtained are given on pages 27-32, which are the sum¬ 
maries of the percentage registration tables found on pages 33-36. 

As the 20 per cent, load mark is the first one on the scale, no numeri¬ 
cal reading is possible unless the indicator is correct or reads too much; 
so on page 27 it is simply noted whether the reading is too large, 
correct or too small. The average registration of those indicators 
which register too much at this point is 113.5 per cent., which is the 
average of the figures appearing on page 33. If those registering 
correctly be included the average is 108.7 per cent. The readings at 
the lower end of the scale are considerably influenced by temperature; 
for instance, four indicators of 35-amperes capacity, were set at 68 de¬ 
grees F., and then the temperature raised to 104 degrees F. and kept 
there for four hours; no current was sent through the indicators. The 
average rise of the liquid in the indicator tubes was .52 inch, which 
roughly corresponds to a change of reading of 5 amperes at this point. 
These extremely low readings are not, however, of as great importance 
as those at the upper end of the scale. For example, it happened that 
the average percentage reading of the indicators when removed for 
test was approximately 60 per cent., with an occasional value falling 
as low as 30 per cent. The effect of temperature becomes smaller as 
the readings increase. 

This is more fully illustrated by the following tests: Two indicators, 
one of 5, the other of 10, amperes’ capacity, were used. They were 
placed in a suitable chamber in which were heating coils and a fan to 
circulate the air. The temperature being originally at 68 degrees F. 
was raised to 104 degrees F., no current being sent through the indi¬ 
cators. The rise of liquid in the index tube was for the 5-ampere 
indicator .38 inches, for the 10-ampere indicator .50 inches. 

The temperature was maintained constant for four hours at 104 
degrees F., the fan being kept running; at the end of this time the 20 
per cent, load test was begun, the other tests followed as usual and the 
results are shown in Fig. 9. It will be seen that the low readings are 
very considerably affected, that the percentage error decreases with 
an increase of load, and that each instrument has its own character- 


26 


APPENDIX A. 


[Jan. 


istic behavior. The results given by the curves are the averages 
obtained from three separate tests. 

The results at the other loads are stated numerically on pages 28- 
29, where are exhibited the number of indicators falling into these 
groups:— 

Indicators registering 90 per cent, and less 

Indicators registering from 90.1 to 94.9 per cent, inclusive. 

Indicators registering from 95 to 98 per cent, inclusive. 

Indicators registering from 98.1 to 101.9 per cent, inclusive. 

Indicators registering from 102 to 105 per cent, inclusive. 

Indicators registering from 105.1 to 109.9 per cent, inclusive. 

Indicators registering 110 per cent, and more. 

From these tables it will be seen that — 

At 20 Per Cent. Load .— Approximately 45 per cent, of the indicators 
register too much with an average excess registration of 13.5 per cent. 

Approximately 31 per cent, of the indicators register too little. 

Approximately 25 per cent, of the indicators register correctly. 

The average excess registration of the indicators which register cor¬ 
rectly and too much is 8.7 per cent. 

At 4.3 Per Cent Load .— Approximately 72 per cent, of the indicators 
register between 95 and 105 per cent. 

Approximately 19 per cent, of the indicators register more than 
105 per cent. 

Approximately 10 per cent, of the indicators register less than 95 
per cent. 

Average registration of 81 meters at 43 per cent, load is 101.3 per 
cent. 

At 66 Per Cent. Load .— Approximately 84 per cent, of the indicators 
register between 95 and 105 per cent. 

Approximately 11 per cent, of the indicators register more than 105 
per cent. 

Approximately 5 per cent, of the indicators register less than 95 
per cent. 

Average registration of 81 meters at 66 per cent, load is 101.1 per 
cent. 

At 90 Per Cent. Load .— Approximately 82 per cent, of the indi¬ 
cators register between 95 and 105 per cent. 

Approximately 14 per cent, of the indicators register more than 105 
per cent. 

Approximately 5 per cent, of the indicators register less than 95 per 
cent. 




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HOUSE —No. 1672. 


27 


Average registration of 81 meters at 90 per cent, load is 101.1 per 
cent. 

References to pages 33-36 will show that there are occasional wide 
deviations from the average values. For instance, among the 150 
ampere indicators tested at 90 per cent, load, there is one with a 
registration of 114.8 per cent., and one with a registration of 110.4 
per cent. All the others average about 103 per cent. 

Results of Tests on 81 Wright Demand Indicators classified 
in Groups according to the Magnitude of the Errors and 
the Sizes of the Indicators. 


At 20 Per Cent. Load. 


Rating of Indicators (Amperes). 

Number of Indicators 

WHICH REGISTER TOO — 

Number 
which register 
correctly. 

Much. 

Little. 

5. 

6 

2 

0 

10,. 

3 

3 

4 

15. 

5 

3 

2 

25. 

5 

4 

1 

35. 

1 

3 

0 

50. 

7 

2 

1 

75.. • 

3 

4 

3 

100,. 

3 

1 

1 

150,. 

3 

0 

4 

200,. 

0 

2i 

4i 

300. 

0 

1 

0 

Totals, . 

36 

25 

20 


i At 25 per cent load being first mark on scale of this indicator. 

44.5 per cent, of the indicators register too much. The average excess registration is 13.5 per 
cent. 

30.9 per cent, of the indicators register too little. 

24.7 per cent, of the indicators register correctly. 

Average excess registration of indicators which register correctly and too much, 8.7 per cent. 
































28 


APPENDIX A. 


[Jan 


Results of Tests on 81 Wright Demand Indicators — Continued. 

At 43 Per Cent. Load. 


Number of Indicators registering — 


Rating 
of Indicators 
(Amperes). 

110 Per 
Cent, and 
More. 

109.9-105.1 
Per Cent, 
inclusive. 

105-102 
Per Cent, 
inclusive. 

101.9-98.1 
Per Cent, 
inclusive. 

98-95 

Per Cent, 
inclusive. 

94.9-90.1 
Per Cent, 
inclusive. 

90 Per 
Cent, and 
Less. 

5, . . . 

0 

0 

2 

4 

2 

0 

0 

10, . 

0 

2 

2 

4 

0 

1 

1 

15, . . . 

0 

0 

3 

3 

4 

0 

0 

25, . . . 

0 

0 

2 

6 

1 

1 

0 

35, . 

1 

0 

2 

0 

0 

1 

0 

50, . 

3 

3 

2 

1 

0 

1 

0 

75, . . . 

1 

0 

1 

4 

4 

0 

0 

100, . 

0 

1 

2 

2 

0 

0 

0 

150, . 

1 

3 

0 

2 

0 

1 

0 

200, . 

0 

0 

0 

5 

0 

1 

0 

300, . 

0 

0 

0 

0 

0 

0 

1 

Totals, 

6 

9 

16 

31 

11 

6 

2 


71.6 per cent 


of the indicators register between 95 per cent, and 105 per cent. 


18.5 per cent, of the indicators register more than 105 per cent. 
9.9 per cent, of the indicators register less than 95 per cent. 


At 66 Per Cent. Load. 




Number of 

Indicators registering — 


Rating 
of Indicators 
(Amperes). 

110 Per 
Cent, and 
More. 

109.9-105.1 
Per Cent, 
inclusive. 

105-102 
Per Cent, 
inclusive. 

101.9-98.1 
Per Cent, 
inclusive. 

98-95 
Per Cent, 
inclusive. 

94.9-90.1 
Per Cent, 
inclusive. 

90 Per 
Cent, and 
Less. 


5, . . . 

0 

0 

1 

2 

4 

1 

0 

10, . . . 

0 

1 

3 

4 

1 

1 

0 

15, . . . 

0 

0 

2 

2 

6 

0 

0 

25, . . . 

0 

0 

1 

7 

1 

1 

0 

35, . . . 

1 

0 

1 

1 

1 

0 

0 

50, . 

2 

1 

4 

3 

0 

0 

0 

75, . . . 

1 

0 

4 

3 

2 

0 

0 

100, . 

0 

1 

2 

2 

0 

0 

0 

150, . 

1 

1 

2 

2 

1 

0 

0 

200, . 

0 

0 

2 

4 

0 

0 

0 

300, . 

0 

0 

0 

0 

0 

1 

0 

Totals, 

5 

4 

22 

30 

16 

4 

0 


84.0 per cent, of the indicators register between 95 per cent, and 105 per cent. 
11.1 per cent, of the indicators register more than 105 per cent. 

5.0 per cent, of the indicators register less than 95 per cent. 































































1912.] 


HOUSE — No. 1672. 


29 


Results of Tests on 81 Wright Demand Indicators — Concluded. 

At 90 Per Cent. Load. 


Number of Indicators registering—• 


Rating 
of Indicators 
(Amperes). 

110 Per 
Cent, and 
More. 

109.9-105.1 
Per Cent, 
inclusive. 

105-102 
Per Cent, 
inclusive. 

101.9-98.1 
Per Cent, 
inclusive. 

98-95 
Per Cent, 
inclusive. 

94.9-90.1 
Per Cent, 
inclusive. 

90 Per 
Cent, and 
Less. 

5, . . . 

0 

• 0 

1 

5 1 

1 

1 

0 

10, . . . 

1 

0 

1 

5 

2 

1 

0 

15, . . 

0 

0 

1 

7 

2 

0 

0 

25, . . . 

0 

0 

1 

6 

2 

1 

0 

35, . 

0 

2 

0 

2 

0 

0 

0 

50, . 

0 

3 

4 

2 

1 

0 

0 

75, . . . 

1 

0 

1 

6 

2 

0 

0 

100, . 

1 

1 

0 

3 

0 

0 

0 

150, . 

2 

0 

3 

0 

2 

0 

0 

200, . 

0 

0 

3 

3 

0 

0 

0 

300, . 

0 

0 

0 

0 

0 

1 

0 

Totals, 

5 

6 

15 

39 

12 

4 

0 


81.5 per cent, of the indicators register between 95 per cent, and 105 per cent. 

13.6 per cent, of the indicators register more than 105 per cent. 


5.0 per cent 


of the indicators register less than 95 per cent. 


Results of Tests on 81 Wright Demand Indicators, as shown by 
the Average Values, classified according to Sizes of the 
Indicators. 

Average Results from 8 5-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

.066 

- 

6.3 

- 

43. 

- 

.016 

- 

.7 

66. 

- 

.050 

- 

1.5 

90. 

- 

.045 

- 

1.0 
















































30 


APPENDIX A. 


[Jan 


Results of Tests on 81 Wright Demand Indicators, as shown by 

the Average Values — Continued. 


Average Results from. 10 10-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

- 

- 

43 . 

.015 


.3 

- 

66. 

.022 

- 

.3 

- 

90. 

- 

.004 

0.0 

0.0 


Average Results from 10 15-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

- 

- 

43 . 

- 

.042 

- 

.6 

66. 

- 

.099 

- 

1.0 

90. 

- 

.13 

- 

1.0 


Average Results from 10 25-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

- 

- 

43. 

- 

.046 

- 

.4 

66, ....... 

- 

.034 

- 

.2 

90. 

- 

.27 

- 

1.2 






















































1912.] 


HOUSE —No. 1672. 


31 


Results of Tests on 81 Wright Demand Indicators, as shown by 

the Average Values — Continued. 

Average Results from 4 35-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

— 


43. 

.54 

- 

3.6 

- 

66,. 

.84 

- 

3.6 

- 

90. 

1.30 

- 

4.1 

- 


Average Residts from 10 50-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

- 

- 

43. 

1.59 

- 

7.3 

- 

66. 

1.29 


3.9 

- 

90 . 

1.55 

- 

3.4 

- 


Average Results from 10 75-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

- 

- 

43 . 

.35 

- 

1.1 

- 

66 . 

.90 

- 

1.8 

- 

90 . 

1.05 

- 

1.5 

- 






















































32 


APPENDIX A 


[Jan 


Results of Tests on 81 Wright Demand Indicators, as shown by 

the Average Values — Concluded. 

Average Results from 5 100-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

- 

- 

43, . 

1.09 

- 

2.5 

- 

66. 

1.40 

- 

2.1 

- 

90,. 

3.44 

- 

3.8 

- 


Average Results from 7 150-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

- 

- 

43, . . ... 

2.3 

- 

3.6 

- 

66,. 

3.3 

- 

3.3 

- 

90,. 

5.1 

- 

3.8 

- 


Average Results from 6 200-Ampere Indicators. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

- 

- 

43. 

- 

.7 

- 

.8 

66. 

2.3 

- 

1.8 

- 

90. 

4.0 

- 

2.2 

- 


Results from 1 300-Ampere Indicator. 


Per Cent, of Full Load. 

Indicators register 
too — 

Corresponding Per 
Cent, too — 

Much by — 
Amperes. 

Little by — 
Amperes. 

Much. 

Little. 

20. 

- 

- 

- 

- 

43. 

- 

18.5 

- 

14.2 

66. 

- 

18.0 

- 

9.0 

90,. 

- 

24.0 

- 

8.8 








































































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N 


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/<0O 
/30 
120 
//O 
/OO 
90 
SO 
70 
60 
SO 
4o 
30 
20 
/0 




v 










\ 

\ 

\ 

N *^ 

/04°f 










V 

"- 

— 







<5^ 

^7^ 











AVc?;? 

1 

c/m am Z?er 

Z me// c cx£,om 

m am 

2/ 




*i 

3. 

/O /4 r-rn f=> G m G s- 

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ft 




















/- > <—/— Og r~/F. oF /^lu // /_ 


o c? 


<=/. 


Fig. 9. 















































































1912.] 


HOUSE —No. 1672 


33 


Percentage Registration of Wright Maximum Demand Indicators. 

At 20 Per Cent. Load. 


Rating of Indicators 
(Amperes). 

Regis¬ 
tering too 

Registra¬ 
tion (Per 

Regis¬ 
tering too 

Registra¬ 
tion (Per 

Register¬ 

ing 

Much. 

Cent.). 

Little. 

Cent.). 

correctly. 

5. 

No. 90193 

101.9 

No. 12885 

95.2 


12441 

125.7 

95049 

95.2 

- 


14409 

102.0 

- 

- 

- 


11 

114.3 

- 

- 

- 


12613 

104.8 

- 

- 

- 


14545 

111.4 

- 


- 

10. 

No. 93352 

110.0 

No. 9838 

_ 

No. 15071 

96157 

102.5 

14285 

- 

8815 


9431 

115.0 

93718 

- 

15464 


- 

- 

- 

- 

13718 

15, ....... 

No. 7208 

118.4 

No. 5603 

— 

No. 6538 

11689 

. 121.7 

5165 

- 

15650 


13819 

115.0 

5551 

- 

- 


2757 

121.7 

- 

- 

- 


2871 

103.3 

- 

- 

- 

25. 

No. 91286 

113.0 

No. 4785 

— 

No. 3729 

6992 

102.0 

4362 

- 

- 


2563 

111.2 

6974 

- 

- 


473 

112.2 

- 

- 

- 


9110 

106.3 

2981 

98.4 

— 

35, ....... 

No. 11880 

101.4 

No. 12448 

— 

— 

— 

— 

10961 

- 

- 


- 

- 

3978 

- 

- 

50. 

No. 11858 

117.5 

No. 90764 

— 

No. 1431 

7661 

170.0 

12030 

- 

- 


4431 

132.5 

- 

- 

- 


3961 

115.0 

- 

- 

- 


6440 

126.0 

- 

- 

- 


3484 

115.0 

- 

- 



10580 

112.5 

- 

— 

— 

75,. 

No. 10984 

113.3 

No. 10914 

— 

No. 3004 

2824 

113.3 

3674 

- 

4582 


142 

103.3 

11342 

- 

4872 


- 

- 

94459 

- 

— 

100. 

No. 3824 

113.8 

No. 90357 

— 

No. 1493 

7562 

111.2 

- 

- 

- 


7563 

106.1 

- 

— 


150. 

No. 90459 

106.7 

— 

- 

No. 13811 

90460 

105.0 

- 

- 

8376 


2098 

111.7 

— 

- 

13555 



- 

- 


2096 

200,. 


_ 

No. 13808 

_ 

No. 90236 

_ 

_ 

11048 

- 

230 


__ 


_ 

— 

237 


- 

- 

- 

- 

298 

300. 

- 

- 

No. 11686 

- 

- 





































34 


APPENDIX A. 


[Jan 


Percentage Registration of Wright Maximum Demand Indicators 

— Continued. 

At 1+3 Per Cent. Load. 


Rating of Indicators 
(Amperes). 

Regis¬ 
tering too 
Much. 

Registra¬ 
tion (Per 
Cent.). 

Regis¬ 
tering too 
Little. 

R egistra- 
tion (Per 
Cent.). 

Register¬ 

ing 

correctly. 

5. 

No. 90493 

102.3 

No. 12441 

98.6 



14545 

104.5 

12885 

96.4 

- 


- 

- 

14409 

98.6 

- 


- 

- 

11 

98.6 

— 


- 

- 

95049 

96.4 

- 


- 

- 

12613 

98.6 

- 

10. 

No. 93352 

106.3 

No. 9838 

89.5 

No. 15071 


96157 

104.0 

14285 

98.1 

- 


8815 

101.2 

15464 

94.6 

— 


9431 

108.2 

94718 

99.3 

- 


13718 

102.3 

- 

- 

- 

15. 

No. 7208 

103.1 

No. 5603 

99.2 

_ 


11689 

100.8 

5165 

96.9 

— 


13819 

102.6 

6538 

95.7 

— 


2757 

104.6 

15650 

95.7 

• - 


- 

- 

5551 

95.4 

- 


- 

- 

2871 

99.5 

- 

25. 

No. 91286 

101.1 

No. 4785 

92.6 

_ 


3729 

103.2 

4362 

98.2 

— 


6992 

101.4 

6974 

96.0 

— 


2563 

104.4 

473 

99.9 

— 


2981 

100.2 

9110 

98.8 

- 

35,. 

No. 12448 

115.8 

No. 10961 

91.1 

_ 


11880 

104.0 

— 

— 

- 


3978 

103.3 

- 

- 

- 

50. 

No. 90764 

103.5 

No. 12030 

92.6 

_ 


11858 

107.6 

— 

— 

— 


7661 

121.5 

— 

— 

— 


4431 

118.1 

— 

— 

— 


3961 

108.8 

— 

— 

— 


6440 

101.4 

— 

— 

_ 


3484 

111.1 

— 

— 

_ 


10580 

106.5 

— 

— 

— 


1431 

102.4 

- 

- 

- 

75,. 

No. 3004 

100.8 

No. 10914 

96.9 

_ 


4582 

101.5 

3674 

96.9 

— 


4872 

101.5 

94459 

96.2 

— 


10984 

103.1 

— 

— 

— 


11342 

101.5 

142 

97.7 

— 


2824 

114.6 

- 

- 

- 

100. 

No. 3824 

103.2 

No. 1493 

99.9 

_ 


7562 

105.1 

— 

_ 

_ 


7563 

102.8 

— 

_ 

_ 


90357 

101.6 

- 

- 

- 

150,. 

No. 13811 

107.7 

No. 8376 

98.5 

. 


90459 

110.0 

2098 

93.8 

— 


90460 

106.2 

_ 

— 

_ 


13555 

100.4 

— 

— 

_ 


2096 

108.6 

- 

- 

- 

200. 

No. 90236 

101.2 

No. 13808 

91.9 

No. 237 


230 

101.2 

11048 

99.1 



298 

101.7 

- 

- 

- 

300. 

- 

- 

No. 11686 

85.8 

- 


Average registration of 81 meters at 43 per cent, load is 101.3 per cent. 



























1912.] 


HOUSE — No. 1672. 


35 


Percentage Registration of Wright Maximum Demand Indicators 

— Continued. 

At 66 Per Cent. Load. 


Rating of Indicators 
(Amperes). 

Regis¬ 
tering too 
Much. 

Registra¬ 
tion (Per 
Cent.). 

Regis¬ 
tering too 
Little. 

Registra¬ 
tion (Per 
Cent.). 

Register¬ 

ing 

correctly. 

5,. 

No. 90433 

100.9 

No. 12441 

92.8 



14909 

100.9 

12885 

97.3 

- 


14545 

104.8 

11 

97.9 

- 


— 

— 

95049 

95.8 

— 


- 

- 

12613 

97.9 

- 

10,. 

No. 93352 

103.3 

No. 9838 

93.5 

— 


96157 

102.6 

14285 

98.8 

- 


15071 

101.5 

15464 

97.3 

- 


8815 

105.3 

13718 

98.5 

- 


9431 

103.4 

93718 

99.2 

- ' 

15. 

No. 7208 

103.5 

No. 5603 

99.5 

No. 13819 


2757 

104.7 

5165 

97.7 

- 


— 

— 

6538 

97.0 

- 


_ 

_ 

15650 

95.7 

- 


_ 

— 

11689 

97.3 

- 


_ 

_ 

5551 

97.2 

- 


- 

- 

2871 

97.5 

- 

25,. 

No. 91286 

101.8 

No. 4785 

92.0 

No. 4362 


3729 

101.6 

473 

99.4 

- 


6992 

100.6 

9110 

96.2 

- 


6974 

101.3 

- 

' - 

- 


2563 

103.1 

- 

- 

- 


2981 

101.8 

— 

- 

— 

35,. 

No. 12448 

114.9 

No. 11880 

99.4 

- 


3978 

103.7 

10961 

96.5 


50,. 

No. 90764 

102.1 

No. 12030 

98.4 

- 


11858 

104.3 

- 


- 


7661 

111.9 

- 

- 



4431 

111.1 

- 

- 

- 


3961 

100.6 

- 

- 

- 


6440 

102.3 

- 

- 



3484 

105.6 

- 

- 

- 


10580 

102.1 

- 

- 

— 


1431 

100.6 

- 

— 


75. 

No. 10914 

102.0 

No. 4872 

99.5 

No. 3674 


3004 

104.0 

94459 

95.0 

- 


4582 

100.5 

142 

95.5 

- 


10984 

102.0 

- 

- 

. “ 


11342 

105.0 

- 


— 


2824 

114.4 

— 

— 

— 

100. 

No. 7562 

103.6 

No. 1493 

99.1 

- 

7563 

102.5 

3824 

99.8 

- 


90357 

105.5 

— 

— 

— 

150, . 

No. 13811 

105.7 

No. 2098 

97.5 

No. 2096 


8376 

100.7 

- 

- 

— 


90459 

114.0 

- 

- 

— 


90460 

103.3 

- 

- 

— 


13555 

102.3 

— 



200,. 

No. 90236 

102.7 

No. 13808 

99.6 

- 


230 

101.2 

- 

— 



237 

101.9 

- 

“ 

— 


298 

101.9 

- 


— 


11048 

103.5 

— 


“ 

300,. 

- 

- 

No. 11686 

91.0 

- 


Average registration of 81 meters at 66 per cent, load is 101.1 per cent. 

































36 


APPENDIX A. 


[Jan. 


Percentage Registration of Wright Maximum Demand Indicators 

— Concluded. 

At 90 Per Cent. Load. 


Rating of Indicators 
(Amperes). 

Regis¬ 
tering too 
Much. 

Registra¬ 
tion (Per 
Cent.). 

Regis¬ 
tering too 
Little. 

Registra¬ 
tion (Per 
Cent.). 

Register¬ 

ing 

correctly. 

5,. 

No. 14109 

101.1 

\ 

No. 12441 

92.3 

No. 90493 


14545 

104.8 

12885 

98.9 

- 


- 

- 

11 

98.9 

- 


- 

- 

229 

98.9 

— 


- 

- 

12613 

97.1 

- 

10,. 

No. 93352 

101.3 

No. 9838 

91.3 

_ 


96157 

100.6 

14285 

98.9 

- 


15071 

102.2 

15464 

98.9 

- 


8815 

110.0 

13718 

97.8 

- 


9431 

101.7 

93718 

96.9 

- 

15. 

No. 2757 

103.0 

No. 5603 

99.6 

No. 7208 


- 

- 

5165 

98.5 

- 


— 

— 

6538 

98.9 

- 


- 

- 

15650 

97.0 

— 


- 

- 

11689 

98.3 

- 


- 

- 

5551 

98.5 

- 


— 

- 

13819 

98.5 

- 


- 

- 

2871 

97.9 

- 

25. 

No. 91286 

102.8 

No. 3729 

99.3 

_ 


4362 

100.9 

6992 

99.3 

— 


2563 

101.0 

4785 

93.0 

- - 


2981 

100.8 

6974 

99.3 

- 


- 

- 

473 

96.7 

- 


- 

- 

9110 

95.2 

- 

35, . 

No. 12448 

108.3 

No. 11880 

99.4 

No. 10961 


3978 

108.8 

- 

- 

- 

50, . 

No. 90764 

102.2 

No. 1431 

98.9 

_ 


11858 

105.0 

12C30 

97.8 

— 


7661 

109.4 

— 

— 

— 


4431 

105.6 

- 

— 

— 


3961 

100.6 

— 

— 

— 


6440 

103.2 

- 

— 

— 


3484 

109.6 


- 

— 


10580 

102.2 

- 

- 

- 

75. 

No. 10914 

100.7 

No. 4872 

99.6 

_ 


3004 

102.6 

94459 

95.6 

— 


3674 

101.8 

142 

97.0 

— 


4582 

101.5 

— 

— 

— 


10984 

101.5 

— 

_ 

— 


11342 

101.8 


— 

— 


2824 

113.2 


- 

- 

100, 

No. 3824 

100.6 

_ 

_ 

No. 1493 


7562 

106.9 

— 

— 

— 


7563 

100.6 

— 

— 

— 


90357 

111-4- 

- 

- 

- 

150. 

No. 13811 

103.7 

No. 2096 

96.7 

_ 


8376 

102.6 

2098 

96.3 

— 


90459 

114.8 

— 

— 

_ 


90460 

102.2 

- 

_ 

_ 


13555 

110.4 

- 

- 

- 

200. 

No. 90236 

101.1 

_ 

_ 

No. 13808 


230 

102.2 

— 

— 

_ 


237 

105.0 

— 

— 

_ 


298 

101.8 

— 

— 

_ 


11048 

103.3 

- 

- 

- 

300. 

- 

- 

No. 11686 

91.2 

- 


Average registration of 81 meters at 90 per cent, load is 101.1 per cent 




































Fig. 10. — Ingalls Relay Demand Indicator 




















































































































II 'lU 


r —i 





Ui 

o > 
c: o 

^ IL CC 
O O Vi 

" * 
o ui 


CONTACTOR for INGALLS RELAY DEMAND INDICATOR 













1912.] 


HOUSE —No. 1672. 


37 


The Ingalls Relay Demand Indicator. 

This device may be regarded as an auxiliary to the watt-hour 
meter by means of which the number of revolutions made by that 
instrument in a given time (half an hour) may be obtained from a 
record impressed on a uniformly moving paper tape. From this 
record, knowing the disc constant of the watt-hour meter and the 
gear ratio of the contact arrangement which is described later, the 
demand may be calculated. 

The Edison Company has 61 of these indicators installed for billing 
purposes (June 30, 1911). 

Fig. 10 shows the general appearance of one of these devices adapted 
to obtain on a single tape the records from two watt-hour meters. A 
very powerful, double-spring clock is used to drive the drum (D) over 
which the paper tape (T) is passed; to prevent slipping of the tape 
the drum is armed with needle points. By the clockwork the tape is 
drawn from the magazine (M) and caused to pass in front of the 
punch (P). W is the take-up roll; it is actuated by a friction drive 
from the clock. 

Whenever a current is passed through one of the magnets of the 
punch (P) the corresponding armature is drawn in and a perfora¬ 
tion made. Once each hour, by the clock, a mark is printed on the 
tape. 

To actuate the punch a contact arrangement is added to the counter 
of the watt-hour meter; this is shown diagrammatically in Fig. 11. 
The wheel (g) is driven by the counter and revolves once for each 
100 revolutions of the meter disc. The contactor (C) and the weight 
(W) are in one piece, which is loose on the shaft. The pin (P) is long 
enough to engage with this piece and then push it to the dotted posi¬ 
tion, when it suddenly falls forward. This causes the contactor (C) 
to connect b and b' (which are in reality in the same plane) for an 
instant, thus closing the circuit through the magnets of the punch, 
which then perforates the tape. After 100 revolutions of the meter 
disc this operation is repeated. The appearance of the record thus 
obtained is seen in Fig. 12. 

The tapes are replaced once a w T eek; when this is done the time of 
the beginning of the record is recorded on the tape, as is the time of 
the ending of the record. 

To find the maximum demand the tapes are examined and those 
parts where the perforations appear to be closest together are selected 
for measurement, a scale of a length corresponding to the motion of 
the tape in half an hour at tha.t point is applied to it, and the number 


38 


APPENDIX A. 


[Jan. 


of whole spaces and fractions in this length is determined. Each one 
of the spaces corresponds to 100 revolutions. Thus the number of 
revolutions made by the watt-hour meter in half an hour is found. 
The ordinary formula for the watt-hour meter is 

N x K x 3600 

Kilowatts = —- t—t— > 

t x 1000 

where N is the number of revolutions of the meter disc occurring in t 
seconds and K is the disc constant of the meter. The kilowatts 
demand corresponding to one space on the paper tape, that is, to 100 
revolutions, if they occurred in one-half an hour would then be 

100 x K x 3600 -y-r 

-= 0.2 K 

30 x 60 x 1000 

If instead of one space in half an hour we have any other number, 
the above is simply multiplied by the number of spaces. To illus¬ 
trate: take the tape shown in Fig. 12 and assume that the disc con¬ 
stant (K) of the watt-hour meter is 25. Then the kilowatts demand 
is given by 

K.W. demand — .2 x 25. x (number of spaces in half an hour). 

Where the perforations are closest together there are 8 spaces in 
half an hour, so the demand is 

0.2 x 25. x 8.0 = 40 K.W. 

It will be noticed that the device gives information of value other 
than the maximum demand, for it tells just how the customer’s load 
varies, and gives the hour at which the maximum demand is reached. 
This may or may not be at the time of the peak of the load on the 
station. 

The accuracy of this device depends on two things: first, the 
accuracy of the watt-hour meter to which it is applied; second, on the 
rate of the clock mechanism. An examination of a number of tapes 
taken at random from the files of the Edison Company showed these 
extreme variations: one clock lost thirty-twm minutes in one hundred 
and sixty-five hours, or on the average was in error by about 3-10 of 
1 per cent. Another clock gained twenty-three minutes in one hun¬ 
dred and sixty-six hours, an average error of a little over 2-10 of 1 
per cent. The error which is of importance is thus that due to the 
watt-hour meter. 

















. 






























' 





Fig. 13.—256430. Type W Polyphase Maximum Demand Indicator 













1912.] 


HOUSE —No. 1672. 


39 


The General Electric Type W Watt Demand Indicator. 

Although this instrument is in common use throughout the State, 
it is not employed by the Edison Electric Illuminating Company of 
Boston, and consequently was not included in the first part of this 
report. 

This device is made for use on alternating current circuits and for 
polyphase work only; it is essentially a polyphase-indicating watt¬ 
meter of the induction type, which is provided with an exceedingly 
strong electromagnetic damping system, so that its response to varia¬ 
tions of the load is rendered very slow. The indications are given on 
a dial which is provided with two pointers, one of which indicates the 
load (subject to the time-lag of the instrument); the other shows the 
sustained maximum to which the load has risen. Fig. 13 gives a 
general view T of the instrument and Fig. 14 shows in diagram its 
essential features. Wj and W 2 are the two wattmeter elements 
which are essential to the measurement of power in the ordinary poly¬ 
phase systems, for, as is usual in such measurements, the “ two watt¬ 
meter method” is here employed; Di is the disc in which currents 
are induced by the elements Wi and W 2 ; these currents react with 
the magnetic fields set up by Wi and W 2 and cause the indication of 
the instrument. The disc is made of brass in order that the effect of 
temperature changes may be minimized; this is because the electrical 
resistance of alloys like brass varies much less with changes of tem¬ 
perature than does that of pure metals, for instance, copper. 

The controlling spring against which the movable system deflects 
is at S. In reality three springs are used in series; this is done in 
order that the movable system may be enabled to make 3 complete 
revolutions without complications arising from the spring being 
twisted too tightly. 

The damping disc (D 2 ) is of copper and rotates between two sets 
of magnets (M and M'); each magnet is adjustable vertically so that 
the strengths of the magnetic fields through which the disc moves 
may be varied; in this manner the strengths of the currents induced 
in the disc when it turns, and consequently the retardation experienced 
by it, may be altered; by this means the rapidity with which the instru¬ 
ment responds to changes of load may be adjusted. It is intended 
that the magnets be so set that 90 per cent, of the registration is pro¬ 
duced in five consecutive minutes. 

The hand (Hi) is driven from the spindle by a system of gearing, 
and moves over a dial graduated in kilowatts; as it moves it pushes 
before it the hand (H 2 ), which is loose on the shaft and provided with 


40 


APPENDIX A. 


[Jan. 


a ratchet (R) and a light spring (S'), which tends to turn the hand 
back against the ratchet; the result is that H 2 is pushed up to the 
maximum by Ip and left there, when (owing to the decrease of the 
load) Hi returns toward zero. The instrument may be set by open¬ 
ing the case and raising the ratchet, this allows S' to return the pointer 
H 2 to zero, Hx being previously turned back to that point. It will 
be seem that this device gives the power which is being used at any 
time, as well as the maximum demand in kilowatts; it gives no indi¬ 
cation of the time when the maximum demand was called for. 







A 1' M * 


A7 




A7' 

(fr^\ 


(Tr\\ 


+-D ia/ 


D. 



M Cib A7 


W 

M 


Fig. 14. 


/oto 0-7 























































































































1912.] 


HOUSE —No. 1672. 


41 


Appendix B. 


THE EDISON ELECTRIC ILLUMINATING COMPANY OF 

BOSTON. 

SCHEDULE OF RATES — COMMERCIAL. 

The following prices for electricity are in force, commencing June 
1, 1910: — 

Schedule A, Lighting Rates. — Applies to all lighting customers who 
do not make yearly agreements, embodying certain guarantees. 

Schedule B, Power Rates. — Applies to all power customers. 

Schedule C, Yearly Lighting Rates. — Applies to all lighting custom¬ 
ers who make yearly agreements, embodying certain guarantees. 

Schedules D and D-l, Permanent Electric Rates. — Apply to all cus¬ 
tomers who make long-term agreements, embodying certain guaran¬ 
tees. 

SCHEDULE —A. 

Lighting Rates — Commercial. 

Electricity for any use will be sold, under this schedule, to any cus¬ 
tomer who has signed an agreement for electric service, embodying the 
terms and conditions of the company. 

A price of 11 cents per kilowatt hour will be charged for all elec¬ 
tricity furnished under this schedule, and the minimum charge will 
be $1 per month per meter. 

SCHEDULE — B. , 

Power Rates — Commercial. 

Electricity for power use will be sold, under the following schedule, 
to any customer who has signed an agreement for electric service, 
embodying the terms and conditions of the company. £ Power ” is 
defined as general motor service, cooking, heating, electroplating, 
charging storage batteries, and similar service, but does not include 
the running of dynamos for electric lighting purposes. 

A price of 12 cents per kilowatt hour will be charged for all elec¬ 
tricity furnished under this schedule, with the following deductions, 
and the minimum charge will be $1 per month per meter: 



42 


APPENDIX B. 


[Jan. 


First Deduction. — A price of 9 cents per kilowatt hour will be 
charged for all electricity furnished in excess of 23 and not exceeding 
103 hours’ use of the demand 1 for each month. 

Second Deduction. — A price of 6 cents per kilowatt hour will be 
charged for all electricity furnished in excess of 103 hours’ use of the 
demand for each month. 

Third Deduction. — Whenever that portion of a customer’s bill 
which is calculated at the 9 cent and 6 cent rate, or both, exceeds $10 
per month, a discount of 70 per cent, will be allowed on such excess 
over $10. 

Fourth Deduction. — Whenever a customer’s bill, after the fore¬ 
going deductions have been made, exceeds $100 per month, a dis¬ 
count of 30 per cent, will be allowed on all in excess of $100. 

Fifth Deduction. — Whenever a customer’s bill, after the foregoing 
deductions have been made, exceeds an average rate of 11 cents per 
kilowatt hour, a deduction will be made to make the average rate 
11 cents per kilowatt hour, but in no case less than $1 per month. 

SCHEDULE — C. 

Yearly Lighting Rates — Commercial. 

Electricity for any use will be sold, under the following schedule, to 
any customer who has signed an agreement for yearly electric service, 
embodying the terms and conditions of the company. 

Fixed Costs. 

A price of $60 per year, payable in equal monthly instalments, will 
be charged per kilowatt of the demand 2 up to and including 15 kilo¬ 
watts. 


1 The demand is the greatest amount of electricity used by the customer at any one time. 
Until such time as the company installs one or more indicators, automatically to determine the 
demand, either in whole or in part, it may estimate the demand. The demand on any circuit, 
when an indicator is installed, will be the average of the regular monthly readings of the indi¬ 
cator, between October 1 and the following February 1 in each year. The demand so determined, 
beginning February 1 of each year, shall be the demand for the next twelve months, except that 
the demand in no case shall be less than 34 of the highest reading during the previous twelve 
months, and in no case shall be less than 1 kilowatt; and provided that if any direct-connected 
elevator (as defined below) be installed the demand shall not be taken at less than 10 kilowatts. 
A direct-connected elevator is defined as being an elevator run in guides and in which the car 
starts at the same time as the motor. The customer has the privilege of having the indicator 
cut out one night in each month, proviced a 48-hour written notice is given to the company. 

2 The demand is the greatest amount of electricity used by the customer at any one time. 
Until such time as the company installs one or more indicators, automatically to determine the 
demand, either in whole or in part, it may estimate the demand, but in no case shall it be taken 
at less than 2 /io of a kilowatt. The demand on any circuit, when an indicator is installed, will be 
the greatest reading of the indicator between November 1 and the following February 1 of each 
year, and the demand so determined, beginning February 1 of each year, shall be the demand 
called for by the agreement for the next twelve months, except that the demand in no case shall 
be less than 34 of the highest reading during the previous twelve months. The customer has 
the privilege of having the indicator cut out one night in each month, provided a 48-hour written 
notice is given to the company. 



1912.] 


HOUSE —No. 1672. 


43 


Hrst Deduction. A price of $36 per year, payable in equal monthly 
instalments, will be charged per kilowatt of the demand for all kilo¬ 
watts exceeding 15 and up to and including 55. 

Second Deduction. A price of $30 per year, payable in equal 
monthly instalments, will be charged per kilowatt of the demand for 
all kilowatts exceeding 55. 

Ihese prices do not include the supply of electricity. 

Running Costs. 

A price of 5 cents per kilowatt hour will be charged for all elec¬ 
tricity furnished under this agreement up to and including 1500 kilo¬ 
watt hours per month. 

First Deduction. — A price of 3 cents per kilowatt hour will be 
charged for all electricity furnished under this agreement exceeding 
1500 kilowatt hours and up to and including 5500 kilowatt hours per 
month. 

Second Deduction. — A price of 2\ cents per kilowatt hour will be 
charged for all electricity furnished under this agreement exceeding 
5500 kilowatt hours per month. 

SCHEDULE —D. 

Permanent Electric Rates. 

Electricity for any use in specified premises will be sold, under the 
following schedule, to any customer who has signed an agreement for 
at least 50 kilowatts of permanent electric service, embodying the 
terms and conditions of the company. 

Fixed Costs. 

A price of $60 per year, payable in equal monthly instalments, will 
be charged per kilowatt of service up to and including 15 kilowatts. 

First Deduction. — A price of $36 per year, payable in equal monthly 
instalments, will be charged per kilowatt of service for all kilowatts 
exceeding 15 and up to and including 55. 

Second Deduction. — A price of $30 per year, payable in equal 
monthly instalments, will be charged per kilowatt of service for all 
kilowatts exceeding 55. 

Third Deduction. — A price of $15 per year, payable in equal 
monthly instalments, will be charged per kilowatt of service for all 
kilowatts exceeding 155, provided that the customer has applied for 
high tension transmission line service. 

These prices do not include the supply of electricity. 


44 


APPENDIX B. 


[Jan. 


Running Costs. 

A price of 5 cents per kilowatt hour will be charged for all electricity 
furnished under this agreement up to and including 1500 kilowatt 
hours per month. 

First Deduction. — A price of 3 cents per kilowatt hour will be 
charged for all electricity furnished under this agreement exceeding 
1500 kilowatt hours and up to and including 5500 kilowatt hours per 
month. 

Second Deduction. — A price of 1J cents per kilowatt hour will be 
charged for all electricity furnished under this agreement exceeding 
5500 kilowatt hours and up to and including 105,500 kilowatt hours 
per month. 

Third Deduction. — A price of If cents per kilowatt hour will be 
charged for all electricity furnished under this agreement exceeding 
105,500 kilowatt hours per month. 

The above prices include lamps and care. 

Optional Deduction. — If lamps and care are not supplied by the 
company, it will deduct from the net amount of the bill, as otherwise 
rendered, \ cent per kilowatt hour. 

Excess Costs. 

The company will provide capacity for intermittent overloads up 
to 40 per cent, in excess of the kilowatts applied for by the customer. 

An excess price of 20 cents per kilowatt hour will be charged for all 
electricity furnished at any time in excess of the kilowatts applied for 
by the customer. 


SCHEDULE —D-l. 

Permanent Electric Rates (Theatrical). 

Electricity for any use in specified premises will be sold under the 
following schedule to any customer who has signed an agreement for 
not over 150 kilowatts of permanent theatrical electric service, embody¬ 
ing the terms and conditions of the company. 

Fixed Costs. 

A price of $2,160 per year, payable in equal monthly instalments or 
in such instalments in advance as are convenient to the customer, will 
be charged. 

This price does not include the supply of electricity. 


LB Ap '13 


1912.] 


HOUSE —No. 1672. 


45 


Running Costs. 

A price of 3 cents per kilowatt hour will be charged for all elec¬ 
tricity furnished under this agreement. 

The above prices include lamps and care. 

Optional Deduction. — If lamps and care are not supplied by the 
company, it will deduct from the net amount of the bill, as otherwise 
rendered, J cent per kilowatt hour. 

Excess Costs. 

An excess price of 20 cents per kilowatt hour will be charged for all 
electricity furnished at any time in excess of 150 kilowatts. 


















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